JEE Main & Advanced Mathematics Differential Equations Question Bank Variable Separable type differential equations

  • question_answer
    The solution of \[\frac{dy}{dx}=\frac{{{e}^{x}}({{\sin }^{2}}x+\sin 2x)}{y(2\log y+1)}\] is            [AISSE 1990]

    A)                 \[{{y}^{2}}(\log y)-{{e}^{x}}{{\sin }^{2}}x+c=0\]

    B)                 \[{{y}^{2}}(\log y)-{{e}^{x}}{{\cos }^{2}}x+c=0\]

    C)                 \[{{y}^{2}}(\log y)+{{e}^{x}}{{\cos }^{2}}x+c=0\]

    D)                 None of these

    Correct Answer: A

    Solution :

                       \[\frac{dy}{dx}=\frac{{{e}^{x}}({{\sin }^{2}}x+\sin 2x)}{y(2\log y+1)}\]                    Þ\[\int_{{}}^{{}}{(2y\log y+y)dy=\int_{{}}^{{}}{{{e}^{x}}({{\sin }^{2}}x+\sin 2x})dx}\]                                 On integrating by parts, we get \[{{y}^{2}}(\log y)={{e}^{x}}{{\sin }^{2}}x+c\].


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